Hot air furnace



Oct. 27, 1942.

J. o. JOHNSTON 2,299,901

HOT AIR FURNACE Filed July 24, 1940 2' Sheets-Sheet 1 l J L7. Jbbnslzm J. o. JOHNSTON 2,299,901

HOT AIR FURNACE Filed July 24, 1940 2 Sheets-Sheet 2 J U Lia/91752 017 Patented Oct. 27, 1942 l t-ti" the tliti itl HOT AIR FURNACE James 0. Johnston, St. l etersburg, Fla., assignor to City Fuel Oil and Coal Company, St. Petersburg, Fla, a corporation of Florida Appiication July 24, 1940, Serial No. 347,316;

2 Claims.

This invention relates generally to hot air furnaces; and more particularly to improved air heating structures designed to heat air rapidly and effectively prior to its discharge into a house or apartment intended to be warmed thereby.

The ma'm object of the invention is to provide an air heating unit in which the hot products of combustion are conducted by a short direct route to a flue, and the air to be warmed is forced around and against all the hot outer surfaces of the combustion chamber and through a series of pipes having their outer surfaces subjected to contact with said products during their passage from the firebox of the furnace to the flue.

Other objects of the invention will become ap parent as the detailed description thereof proceeds.

In the drawings:

Fig. 1 is a central longitudinal vertical section through the furnace forming the subject matter of this application;

Fig. 2 is a vertical transverse section taken on the line 2-2 of Fig. 1;

Fig. 3 is a horizontal section taken on the line 33 of Fig. 1; and

Fig. 4 is a horizontal section taken on the line 4-4 of Fig. 1.

As shown in the drawings, the furnace comprises a double-walled casing, designated generally by the reference numeral 5. The front wall 6 of this casing has an aperture 1 formed therein to give access to the combustion chamber 9; and closure plate 8, fitting snugly in said aperture, forms a mount for the burner it) which projects rearwardly from said plate into the combustion chamber 9 and through the front wall of a refractory brick fire-box I I built upon and supported by the bottom l2 of said combustion chamber.

The chamber is supported mainly by standards I3, which also serve to space the bottom of the chamber from'the furnace-supporting floor to form a conduit for part of the air to be heated. The side walls It and 15 of said chamber are of inverted -shape and extend vertically upward from the bottom I2 to be connected at their upper ends to the opposite edges of the top 16. The front wall of the chamber 9 connects the front edge of the bottom [2 to the front edge of the top It and is provided with an aperture fitting closely around the flange [8 extending as a lining for the aperture 1 from the front wall 6.

The inverted L-shaped rear wall IQ of the chamber 9 extends upwardly from the bottom I2 for connection to the correspondingly shaped edges of the side walls i l and it. The rear upper end of this inverted L-shaped combustion chamber is closed by a wall 29, and the products of combustion are conducted therefrom by a flue 2| extending from the top of said chamber near the wall 20 and through the double walled top 22 of the casing 5.

This inverted L-shaped combustion chamber forms a comparatively large reservoir for the hot products of combustion, and therefore presents large surface areas adapted to transfer heat rapidly to the air directed against it in its flow through the furnace. To increase the area of these heating surfaces, without increasing the over-all size of the furnace, a series of pipes 23 are arranged horizontally in the upper part of the combustion chamber with their opposite ends extending through front and rear walls I! and 20, which are provided with suitable apertures to receive said ends with gastight fit.

As shown clearly in the drawings, the bottom l2 of the combustion chamber Bis raised above the furnace supporting floor, and all the walls of said chamber are spaced inwardly from the adjacent walls of the casing 5 to form conduits through which the air to be warmed may be circulated and moved in heat exchange contact with the hot chamber walls from an air inlet chamber 24 to the hot air register or outlet 25. This air inlet chamber 24 is formed by a partition 2'6, spaced rearwardly from the wall I9 of the combustion chamber and provided with an aperture 21 to receive the air discharge outlet of a blower 28.

The curved bottom wall 32 of the register is connected at its top, adjacent to the upper edge of the wall 29 and is provided at the sides of the lower edge with narrow walls 33 and 24. Below the wall 32 in the chamber 38 is located the blower 28 with its delivery end located to cover the aperture 21. and having its receiving opening covered by a filter plate 3!. This plate 3| may be supported in proper position, accessible for re placement or repair, on the furnace supporting floor or on the framework. The blower 28, which may be driven by any suitable motive power, is preferably connected to theair inlet chamber by a flexible connection 32; and, also is preferably supported by suitable means designed to reduce ing of the parts separately for convenience in assembling or repair involves nothing more than the skill of the mechanic.

What I claim is:

1. A hot air furnace comprising a casing having a forward compartment and a rear compartment and a partition therebetween, an inverted L-shaped heater in, and spaced from the walls of. the forward compartment, an outlet opening from the rear compartment to the forward compartment and in position to deliver air to the lower end of the heater. the heater including a combustion chamber in position to have its walls contacted by air from the opening. the heater having front to rear heater tubes. partition means for confining the movement of air. to pass around the combustion chamber walls and upwardly to the forward ends of the heater tubes and forward portions of the spaces at the sides of the heater and a conduit means in the rear chamber for delivery of the air from the rear ends of the heater tubes and the spaces around the heater.

2. A hot air furnace comprising a casing having a forward compartment and a rear compartment and a partition therebetween, an inverted L-shaped heater in, and spaced from the walls of, the forward compartment, an outlet opening from the rear compartment to the forward compartment and in position to deliver air to the lower end of the heater, the heater including a combustion chamber in position to have its walls contacted by air from the opening, the heater having front to rear heater tubes, partition means for confining the movement of air to pass around the combustion chamber walls and upwardly to the forward ends of the heater tubes and forward portions of the spaces at the sides of the heater, a conduit means in the rear chamber for delivery of the air from the rear ends of the heater tubes and spaces around the heater and an air propelling means in the rear chamber to deliver air to the opening.

, JAMES O. JOHNSTON. 

